I haven't heard that, but in the culinary world as far as I know pastry cream or creme patissierie, is more of a pastry/cake filling, like lemon curd would be. You can use it to fill cream puffs, eclairs and cakes like you would a boston cream pie. I wouldn't think with most recipes it would be good for the outside covering, it contains a lot of milk.But, maybe the word is interchangeable to some, just like some buttercream doesn't contain butter!